Figure 3

p75NTR is involved in Aβ transport through choroid plexus. A double-chamber choroid plexus epithelial cell-culture system mimicking the blood-CSF interface was used for in vitro studies A) Figure 3A shows a scheme of one of these chambers. Choroid plexus epithelial cells were grown in the floor of the upper compartment on the top of a porous membrane. Aβ1-40 5 μg/μL was added to the upper chamber. For inhibition of p75NTR biological activity experiments, prior Aβ1-40 were added in the upper chamber, where we had inhibited the p75NTR activity incubating 24 hours with high concentrations (1:50) of p75NTR antibody directed against extracellular domain (9651). B) In control cells Aβ is normally translocated to the lower chamber, however the cells with p75NTR biological activity inhibiting Aβ translocation was interrupted. TTR is a protein specifically synthesized in the brain by the choroid plexus and associated with Aβ transport via megalin in the choroid plexus. Interestingly, we evidenced that the inhibition of p75NTR biological activity induced a strong secretion of TTR to the upper chamber. C) Inhibition of p75NTR biological activity increased TTR expression in the choroid plexus cells. Representative blots are shown.